#include <stdio.h>
#include <string.h>
#include "mono-digest.h"

static void md5_transform(guint32 buf[4], const guint32 in[16]);

static gint _ie = 0x44332211;
static union _endian {gint i; gchar b[4];}; *_endian = (union _endian*)&_ie;
#define IS_BIG_ENDIAN() (_endian->b[0] == '\x44')
#define IS_LITTLE_ENDIAN() (_endian->b[0] == '0x11')

static void
_byte_reverse(guchar* buf, guint32 longs)
{
	guint32 t;
	do 
	{
		t = (guint32) ((guint32) buf[3] << 8 | buf[2]) << 16 |
			((guint32) buf[1] << 8 | buf[0]);
		*(guint32*)buf = t;
		buf += 4;
	} while (--longs);
}

void
mono_md5_init(MonoMD5Context* ctx)
{
	ctx->buf[0] = 0x67452301;
	ctx->buf[1] = 0xefcdab89;
	ctx->buf[2] = 0x98badcfe;
	ctx->buf[3] = 0x10325476;

	ctx->bits[0] = 0;
	ctx->bits[1] = 0;

	if (IS_BIG_ENDIAN())
		ctx->doByteReverse = 1;
	else
		ctx->doByteReverse = 0;
}

void
mono_md5_update(MonoMD5Context* ctx, const guchar* buf, guint32 len)
{
	guint32 t;

	t = ctx->bits[0];
	if ((ctx->bits[0] = t + ((guint32) len << 3)) < t)
		ctx->bits[1]++;
	ctx->bits[1] += len >> 29;
	t = (t >> 3) & 0x3f;

	if (t)
	{
		guchar *p = (guchar *) ctx->in + t;
		t = 64 - t;
		if (len < t)
		{
			memcpy(p, buf, t);
			return;
		}
		memcpy (p, buf, t);
		if (ctx->doByteReverse)
			_byte_reverse(ctx->in, 16);
		md5_transform(ctx->buf, (guint32*)ctx->in);
		buf += t;
		len -= t;
	}

	while (len >= 64)
	{
		memcpy(ctx->in, buf, 64);
		if (ctx->doByteReverse)
			_byte_reverse(ctx->in, 64);
		md5_transform(ctx->buf, (guint32*)ctx->in);
		buf += 64;
		len -= 64;
	}

	memcpy(ctx->in, buf, len);
}

void
mono_md5_final(MonoMD5Context* ctx, guchar digest[16])
{
	guint32 count;
	guchar* p;

	count = (ctx->bits[0] >> 3) & 0x3F;
	p = ctx->in + count;
	*p++ = 0x80;

	count = 64 - 1 - count;

	if (count < 8)
	{
		memset (p, 0, count);
		if (ctx->doByteReverse)
			_byte_reverse(ctx->in, 16);
		md5_transform(ctx->buf, (guint32*)ctx->in);

		memset(ctx->in, 0, 56);
	}
	else
	{
		memset(p, 0, count - 8);
	}
	if (ctx->doByteReverse)
		_byte_reverse(ctx->in, 14);

	((guint32*)ctx->in)[14] = ctx->bits[0];
	((guint32*)ctx->in)[15] = ctx->bits[1];

	md5_transform(ctx->buf, (guint32*)ctx->in);
	if (ctx->doByteReverse)
		_byte_reverse((guchar*)ctx->buf, 4);
	memcpy(digest, ctx->buf, 16);
}

#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

#define MD5STEP(f, w, x, y, z, data, s) \
	( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

static void 
	md5_transform (guint32 buf[4], const guint32 in[16])
{
	register guint32 a, b, c, d;

	a = buf[0];
	b = buf[1];
	c = buf[2];
	d = buf[3];
	MD5STEP (F1, a, b, c, d, in[0] + 0xd76aa478, 7);
	MD5STEP (F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
	MD5STEP (F1, c, d, a, b, in[2] + 0x242070db, 17);
	MD5STEP (F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
	MD5STEP (F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
	MD5STEP (F1, d, a, b, c, in[5] + 0x4787c62a, 12);
	MD5STEP (F1, c, d, a, b, in[6] + 0xa8304613, 17);
	MD5STEP (F1, b, c, d, a, in[7] + 0xfd469501, 22);
	MD5STEP (F1, a, b, c, d, in[8] + 0x698098d8, 7);
	MD5STEP (F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
	MD5STEP (F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
	MD5STEP (F1, b, c, d, a, in[11] + 0x895cd7be, 22);
	MD5STEP (F1, a, b, c, d, in[12] + 0x6b901122, 7);
	MD5STEP (F1, d, a, b, c, in[13] + 0xfd987193, 12);
	MD5STEP (F1, c, d, a, b, in[14] + 0xa679438e, 17);
	MD5STEP (F1, b, c, d, a, in[15] + 0x49b40821, 22);

	MD5STEP (F2, a, b, c, d, in[1] + 0xf61e2562, 5);
	MD5STEP (F2, d, a, b, c, in[6] + 0xc040b340, 9);
	MD5STEP (F2, c, d, a, b, in[11] + 0x265e5a51, 14);
	MD5STEP (F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
	MD5STEP (F2, a, b, c, d, in[5] + 0xd62f105d, 5);
	MD5STEP (F2, d, a, b, c, in[10] + 0x02441453, 9);
	MD5STEP (F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
	MD5STEP (F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
	MD5STEP (F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
	MD5STEP (F2, d, a, b, c, in[14] + 0xc33707d6, 9);
	MD5STEP (F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
	MD5STEP (F2, b, c, d, a, in[8] + 0x455a14ed, 20);
	MD5STEP (F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
	MD5STEP (F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
	MD5STEP (F2, c, d, a, b, in[7] + 0x676f02d9, 14);
	MD5STEP (F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

	MD5STEP (F3, a, b, c, d, in[5] + 0xfffa3942, 4);
	MD5STEP (F3, d, a, b, c, in[8] + 0x8771f681, 11);
	MD5STEP (F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
	MD5STEP (F3, b, c, d, a, in[14] + 0xfde5380c, 23);
	MD5STEP (F3, a, b, c, d, in[1] + 0xa4beea44, 4);
	MD5STEP (F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
	MD5STEP (F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
	MD5STEP (F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
	MD5STEP (F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
	MD5STEP (F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
	MD5STEP (F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
	MD5STEP (F3, b, c, d, a, in[6] + 0x04881d05, 23);
	MD5STEP (F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
	MD5STEP (F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
	MD5STEP (F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
	MD5STEP (F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

	MD5STEP (F4, a, b, c, d, in[0] + 0xf4292244, 6);
	MD5STEP (F4, d, a, b, c, in[7] + 0x432aff97, 10);
	MD5STEP (F4, c, d, a, b, in[14] + 0xab9423a7, 15);
	MD5STEP (F4, b, c, d, a, in[5] + 0xfc93a039, 21);
	MD5STEP (F4, a, b, c, d, in[12] + 0x655b59c3, 6);
	MD5STEP (F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
	MD5STEP (F4, c, d, a, b, in[10] + 0xffeff47d, 15);
	MD5STEP (F4, b, c, d, a, in[1] + 0x85845dd1, 21);
	MD5STEP (F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
	MD5STEP (F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
	MD5STEP (F4, c, d, a, b, in[6] + 0xa3014314, 15);
	MD5STEP (F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
	MD5STEP (F4, a, b, c, d, in[4] + 0xf7537e82, 6);
	MD5STEP (F4, d, a, b, c, in[11] + 0xbd3af235, 10);
	MD5STEP (F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
	MD5STEP (F4, b, c, d, a, in[9] + 0xeb86d391, 21);

	buf[0] += a;
	buf[1] += b;
	buf[2] += c;
	buf[3] += d;
}

void
mono_md5_get_digest(const guchar* buffer, gint buffer_size, guchar digest[16])
{
	MonoMD5Context context;

	mono_md5_init(&ctx);
	mono_md5_update(&ctx, buffer, buffer_size);
	mono_md5_final(&ctx, digest);
}

void
mono_md5_get_digest_from_file(const gchar* filename, guchar digest[16])
{
	MonoMD5Context ctx;
	guchar tmp_buf[1024];
	gint nb_bytes_read;
	FILE* fp;

	mono_md5_init(&ctx);
	fp = fopen(filename, "r");
	if (!fp)
	{
		return;
	}

	while((nb_bytes_read = fread(tmp_buf, sizeof(guchar), 1024, fp)) > 0)
		mono_md5_update(&ctx, tmp_buf, nb_bytes_read);

	if (ferror(fp))
	{
		fclose(fp);
		return;
	}
	else
	{
		fclose(fp);
	}

	mono_md5_final(&ctx, digest);
}
